1. Field of the Invention
The present invention relates to the removal of skin from defeathered whole leg or drumstick poultry products, primarily from chicken.
2. Description of Background Art
In the field a whole leg poultry product is a commonly accepted term to identify a poultry leg formed by the drumstick and the thigh connected to the drumstick. Other terms used for this product are anatomical leg and separated leg.
In EP 519 570 a system for skin removal from defeathered whole leg poultry products is disclosed. This known system comprises a poultry products conveyor with a track and a series of poultry product carriers which are spaced apart from one another in the direction of the track and which are movable along said track. Each poultry product carrier is adapted to hold a defeathered whole leg poultry product at the ankle joint thereof, also called tarsal joint, such that the poultry product is conveyed hanging from said carrier.
In EP 519 570 it is explained that the poultry product may be passed along a cutting device arranged along the track of the poultry products conveyor in order to make one or more incisions and then along a skin removal device arranged along the track of the poultry products conveyor in order to remove skin from the poultry products held and conveyed by the poultry products conveyor. It is explained, as is commonly done in the field, that the skin is cut through at the knee joint, and that subsequently the thigh skin is removed whilst skin remains on the drumstick. In an embodiment of this prior art system the skin removal device comprises a left and right skin removal assembly, each adapted to remove skin from the thigh of a whole leg poultry product. Each skin removal assembly comprises two rotary driven skinning rollers having an axis of rotation and being driven in opposite directions so that the skin is gripped in the nip between the rollers and pulled from the thigh.
In EP 519 570 the skinning rollers of each assembly are arranged with their axes of rotation parallel to the track of the conveyor in a substantially horizontal orientation, possibly pivotable about an axis transverse to the skinning rollers to obtain a fixed or variable slanted position. The thigh of the hanging whole leg poultry product is then dragged by the conveyor over the skinning rollers, and as a result the thigh skin is gripped by the rotating skinning rollers and the skin is pulled from the thigh.
WO00/5931, on which the preamble of claim 1 is based, discloses in particular with reference to FIGS. 6, 7, and 8 therein a similar system as discussed with reference to EP 519 570. In this prior art document it is discussed that drumstick poultry products, in particular of chicken, are conveyed whilst hanging from a carrier. Each carrier carries two drumsticks in side-by-side arrangement; first along a cutting device that makes a cut in each drumstick near the ankle joint and then along a skin removal device. As in EP 519 570 this device has two skin removal assemblies that each comprises two rotary driven skinning rollers having an axis of rotation and being driven in opposite directions so that the skin is gripped in the nip between the rollers and pulled from the drumstick. The skinning rollers of each assembly are arranged with their axes of rotation parallel to the track of the conveyor in a substantially horizontal orientation.
In WO00/59311 it is indicated that the drumsticks will have the tendency to “dance” on the skinning rollers, leading to poor skin removal results. To counter this effect it is disclosed that the holding part of the carrier is tilted about a horizontal axis relative to the carrier base whilst the carrier passes the skin removal device. The tilting of the holding part causes the drumsticks to be pressed onto the skinning rollers.
The prior art systems are not entirely satisfactory in view of the skin removal results. In particular skin may become torn and thus only fractionally removed and thus requiring undue manual trimming of the poultry product later on. Also occasionally damage to meat of the drumstick or thigh is observed.